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Olivier Biot
Amused
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Reged: 04/25/05

Loc: 51°N (Belgium)
The ‘English Fraunhofer’: Resolving a Paradox?
      #4812254 - 09/17/11 07:53 AM

The ‘English Fraunhofer’: Resolving a Paradox?

By Neil English.


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jrbarnett
Eyepiece Hooligan
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Reged: 02/28/06

Loc: Petaluma, CA
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: Olivier Biot]
      #4812583 - 09/17/11 11:27 AM

Bene scriptum est opus.

Nicely done Neil. Great read. Thanks for submitting the piece.

- Jim

Edited by jrbarnett (09/17/11 11:36 AM)


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Jeff Morgan
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Reged: 09/28/03

Loc: Prescott, AZ
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: Olivier Biot]
      #4812646 - 09/17/11 11:57 AM

A very enjoyable article Neil. They really are timeless scopes.

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hyia
member


Reged: 11/07/10

Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: Olivier Biot]
      #4812792 - 09/17/11 01:27 PM

Thank you for sharing what was obviously the result of a significant amount of research on your part. I've read a number of posts espousing the benefits of longer focal ratio refractors. I'm curious as to where you draw the limit, if any. i.e. It appears that the benefit is linked to the actual focal ratio for whatever reason rather than the lack of false color or ease of figuring. Otherwise, I would think that a high quality doublet of lower focal ratio would be just as good.

So, assuming "good" optical quality, it seems there is a performance benefit of a 4" f11 over a 4" f9. (Assume we are talking about planetary or double star performance.) Would then a 4" f15 of similar quality be even better, and a 4" f20 better still?

I realize this question is not well defined and appreciate any answer you can give. Also, do you have any recommendations for commercially available 4" refractors? Thank you.


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7331Peg
Sirius Observer
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Reged: 09/01/08

Loc: North coast of Oregon
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: Olivier Biot]
      #4812853 - 09/17/11 02:07 PM

A great piece of work, Neil. It took well over an hour to read through it because I kept getting stuck on the photos of those beautiful Cooke refractors. Stupendous works of optical and visual art.



John


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ukcanuck
Vendor (Skylight Telescopes)
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Reged: 11/07/06

Loc: London, UK
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: 7331Peg]
      #4812922 - 09/17/11 02:47 PM

The Fry Telescope at Mill Hill (I just can't bring myself to say the Fry Cooke ), is one of the most impressive telescopes I've ever seen. There's some information on the restoration here.

It's always surprised me how little information there is online about T. Cooke and Sons. Thanks for your effort Neil, this is a great read.


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David Castillo
Carpal Tunnel
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Reged: 09/09/06

Loc: Carmel Valley, Ca
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: ukcanuck]
      #4813123 - 09/17/11 05:08 PM

A gem of an article, Neil. I am awed by these instrument's incredible focal lengths. As you point out, by today's diminishing observing conditions, our needs in a telescope have evolved, but history has proven the quest for superior optics has never faltered. Scopes that sport double digit focal lengths, although often criticized as anachronisms, cannot truly be appreciated until one has the good fortune to be able to look through one. Thank you for the great read.
---
Dave


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Adam Taylor
insignificant bystander
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Reged: 11/11/10

Loc: Arizona
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: Olivier Biot]
      #4813226 - 09/17/11 06:20 PM

Wonderfully written.

Some people dream of having an Italian supermodel for a wife. Others, a fancy sports car parked in their driveway. I dream of a permanently-mounted long-focus achromat.


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Astrojensen
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Reged: 10/05/08

Loc: Bornholm, Denmark
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: Adam Taylor]
      #4814046 - 09/18/11 04:37 AM

Quote:

Some people dream of having an Italian supermodel for a wife. Others, a fancy sports car parked in their driveway.




Forget about these. Too expensive in initial purchase, maintenance and running costs.

Quote:

I dream of a permanently-mounted long-focus achromat.




Now you're talking!


Clear skies!
Thomas, Denmark


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Lightning
sage


Reged: 07/04/10

Loc: Canberra, Australia
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: Astrojensen]
      #4814109 - 09/18/11 06:43 AM

Thank you Neil for such a wonderfully researched and beautifully written article!

I first used the 9" Cooke (F/15 triplet) at Carter Observatory in Wellington, New Zealand when I was 7 years old on a public night and got to see Alpha Centauri and Alpha Crucis. When I was 14 I was very fortunate to be taken on as evening assistant running the telescopes at the observatory and got to enjoy many more sights through both this scope and the 6" F/18 that had been the main telescope of the late Peter Read. Both are amazing instruments, the colour correction of the Cooke triplet providing very true views of double stars.

Sadly the glass in the 9" deteriorated rapidly in the late '90s and was replaced with a larger 9-3/4" achromatic objective crafted by Gary Nankivell (sadly now also departed). At the same time it was expertly restored by Gordon Hudson and Stewart Mawson to the same black & brass as the Fry telescope.

So much history is attached to this scope and those like it.

Thank you so much again for bringing back so many happy memories with the Cooke's I've got spend time with.

Best wishes,
Cameron Jack


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buddyjesus
Carpal Tunnel
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Reged: 07/07/10

Loc: Davison, Michigan
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: Lightning]
      #4814551 - 09/18/11 01:05 PM

Fantastic article

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astroneil
Pooh-Bah
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Reged: 07/28/09

Loc: res publica caledoniae
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: buddyjesus]
      #4815991 - 09/19/11 10:27 AM

Thank you all very much for your kind words.

Kind Regards,

Neil.


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jrbarnett
Eyepiece Hooligan
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Reged: 02/28/06

Loc: Petaluma, CA
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: Olivier Biot]
      #4816009 - 09/19/11 10:36 AM

So, would that make Faunhofer the "Bavarian Cooke"?

- Jim


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KennyJ
The British Flash
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Reged: 04/27/03

Loc: Lancashire UK
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: jrbarnett]
      #4816260 - 09/19/11 01:25 PM

A truly wonderful , brilliant piece of work , as thoroughly researched , well - written , superbly illustrated and enjoyable to read as I could possibly hope any published book on the subject could be .

And all for FREE !

Thank you , Neil !

Kenny


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Mr Onions
Two Time International Photographical Competition Winner
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Reged: 04/14/07

Loc: Newcastle upon Tyne.
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: KennyJ]
      #4816544 - 09/19/11 04:09 PM

You see that white spot on Saturn by the famous comedian/actor Will Hay.
He was funny.


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rookie
Good Night Nurse
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Reged: 01/14/06

Loc: St. Petersburg, FL
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: Mr Onions]
      #4816881 - 09/19/11 07:17 PM

I really enjoyed reading your article, Neil. It's a great history lesson for us to appreciate those that built the foundations of knowledge for our modern telescopes.

The Fry telescope is such a beautiful restoration. If I ever get to London, I'd love to go and see it.


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astroneil
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Reged: 07/28/09

Loc: res publica caledoniae
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: rookie]
      #4819732 - 09/21/11 09:46 AM

Thanks Kenny & Rookie,

My up-and-coming book will also feature a piece on the restoration of Sir Patrick Moore's 5" f/12 Cooke refractor by Steve Collingwood at Telescope House, which is housed in Sir Patrick's observatory at Selsey, on the West Sussex coast.

Some basic info here:

http://www.telescopehouse.com/acatalog/Patrick_Moore_Cooke_Telescope_Restoration.html

Steve was kind enough to provide some amazing insights into the quality of this instrument - both mechanical and optical.

Kind Regards,

Neil.

Edited by astroneil (09/21/11 09:47 AM)


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ukcanuck
Vendor (Skylight Telescopes)
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Reged: 11/07/06

Loc: London, UK
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: rookie]
      #4820105 - 09/21/11 01:22 PM Attachment (292 downloads)

Quote:

The Fry telescope is such a beautiful restoration. If I ever get to London, I'd love to go and see it.




UCL/Mill Hill did a beautiful job on this refractor. An interesting bit of trivia on this is that the focuser had been polished so many time, the T Cooke and Sons engraving had almost been polished away.

To keep it disappearing forever, the restoration team encased the focuser in plexiglass. This keep the brass from tarnishing and it looks great. It also creates something of a 'museum piece' feel about the focuser.

A (not very good) picture here:


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ukcanuck
Vendor (Skylight Telescopes)
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Reged: 11/07/06

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Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: ukcanuck]
      #4822003 - 09/22/11 01:44 PM Attachment (293 downloads)

A recent trip to the South of France brought me to a little town called Puimichel, where I met a gentleman named Jean Baptiste who owns owns a 9" T. Cooke and Sons objective.

He found the refractor in a terrible state some years ago in a forgotten back garden exposed to the elements. Its' origins date to around 1930, when the objective travelled from York, was housed in a majestic ota built by the French company Manent, and was originally placed in a stately home just a few miles from where it currently resides.

When JiBe found it, it was in a terrible state (birds were living in the ota!)

Some background (and lots of pictures) can be found here. This is a Google translation, so the French (and English) will be a little awkward.

My first foray in Youtube is a short video of this scope in it's roll-off observatory: La lunette du père JOSSET

Edited by ukcanuck (09/23/11 04:06 AM)


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7331Peg
Sirius Observer
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Reged: 09/01/08

Loc: North coast of Oregon
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: ukcanuck]
      #4822986 - 09/23/11 12:55 AM

Amazing, amazing, amazing. It'll take a week to dry my desk off after looking at that. Normally red wouldn't be my first choice for a scope, but I'll gladly make an exception in this case!

Did you get a chance to look through it, Richard?


John


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astroneil
Pooh-Bah
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Reged: 07/28/09

Loc: res publica caledoniae
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: 7331Peg]
      #4823308 - 09/23/11 09:00 AM

Richard,

Thanks for posting some additional info on this large Cooke.

Too right John, the personal story of the restorer of this great instrument is a sombre one. Let's hope that Jean Baptiste can continue to use it for many years to come.

I found another Cooke refractor on the other side of the world; this time it's a majestic 9.75" located at Carter Observatory, Wellington, New Zealand.
You can see it beginning from around 1:40 on this video:

http://www.youtube.com/watch?v=gISjfPQzzM0

There’s just under 20 seconds of it, but it looks fabulous and its similarity to the Fry refractor is rather obvious.

You also get a good sense of its scale and there's a haunting, 'Sagan-esque' voice over that draws you in.

Regards,

Neil.


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GlenM
Vendor - Lyra Optic


Reged: 05/20/07

Loc: Lancashire England
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: astroneil]
      #4824086 - 09/23/11 05:51 PM

Neil,

This is one of the best articles I have read in the past few years.

Thank you so much for all your hard work


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ukcanuck
Vendor (Skylight Telescopes)
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Reged: 11/07/06

Loc: London, UK
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: 7331Peg]
      #4826540 - 09/25/11 09:57 AM Attachment (35 downloads)

Quote:

Did you get a chance to look through it, Richard?

John




Sorry for the delay...was away and got distracted.

The weather was amazing when I was in France...40 degrees and clear every night. I was in Puimichel for two of these nights. The wind kept us from opening the observatory the first night, but the second night was fine, and the big refractor didn't disappoint.

The scope is so majestic and overwhelming, that when I looked through it I felt like one of its' accessories!

Picture of the cell with the remote doors open (I say remote, but it's really a long string that you pull...very cool ).


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astroneil
Pooh-Bah
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Reged: 07/28/09

Loc: res publica caledoniae
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: GlenM]
      #4852432 - 10/09/11 04:52 PM

Quote:

Neil,

This is one of the best articles I have read in the past few years.

Thank you so much for all your hard work




Glen,

Thank you very much for the compliment. It did take quite an effort to gather all the information together, but I think it was worth it in the end.

I found a link to a fairly comprehensive overview of a smaller (3.25") Cooke; 'The Doncaster'.

It provides a good insight into the quality of the workmanship that went into even the smallest of these instruments.

http://articles.adsabs.harvard.edu//full/2000IrAJ...27...55A/0000055.000.html

Regards,

Neil.


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bluestar
Carpal Tunnel


Reged: 11/06/05

Loc: Maryland Eastern Shore
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: Adam Taylor]
      #4853613 - 10/10/11 10:33 AM

Quote:

Wonderfully written.

Some people dream of having an Italian supermodel for a wife. Others, a fancy sports car parked in their driveway. I dream of a permanently-mounted long-focus achromat.




At the risk of a major 'net faux pas...Ditto.


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rguasto
professor emeritus
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Reged: 11/18/10

Loc: Long Island, NY
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: Olivier Biot]
      #4855427 - 10/11/11 09:56 AM

Thank you for taking the time to write that and share it with us.
-Rob


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Ed Holland
Pooh-Bah


Reged: 06/16/10

Loc: San Jose, CA and Oxford, UK
Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: rguasto]
      #4855878 - 10/11/11 02:21 PM

Thank you Neil, for this well researched and superbly written article - most enjoyable.

Cheers,

Ed

P.S. I find it more than appropriate (and amusing) that there are features on long achromatic telescopes on... Youtube


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astroneil
Pooh-Bah
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Reged: 07/28/09

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Re: The ‘English Fraunhofer’: Resolving a Paradox? new [Re: Ed Holland]
      #4860663 - 10/14/11 11:19 AM

Pat, Rob & Ed;

Thank you very much for your comments. They mean a great deal to me.

Yep, despite all the marvellous innovations of our age, these old telescopes continue to fascinate me.

Indeed, intellectually, I find them (long focus achromats) to be the most engaging of all telescopes. They just have so many remarkable properties!

I suppose you could say that when it comes to refractors, I have Catholic taste. Notwithstanding the temptation from a suite of impressive new performers with low dispersion glass, I'd much rather have a traditional 6" f/15, plain and simple.

With best wishes,

Neil.

Edited by astroneil (10/14/11 12:30 PM)


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